$TIMEOUT - Revision history

Admin: Created page with "= Action = Enable timeout on the hardware UART and software UART.
2013-02-06T21:56:54Z

Created page with "= <span class="f_Header">Action</span> = Enable timeout on the hardware UART and software UART. <span style="font-family: Arial;"> </span> <span style="font-family: Ar..."

New page
= <span class="f_Header">Action</span> =

Enable timeout on the hardware UART and software UART.

<span style="font-family: Arial;"> </span>

<span style="font-family: Arial;"> </span>

= <span class="f_Header">Syntax</span> =

<span class="f_Syntax">$TIMEOUT</span> = value

<span style="font-family: Arial;"> </span>

<span style="font-family: Arial;"> </span>

= <span class="f_Header">Remarks</span> =
<div style="padding: 0px; margin: 0px 0px 0px 4px;">
{| width="631" cellspacing="0" cellpadding="1" border="1" style="border: 2px solid rgb(0, 0, 0); border-spacing: 0px; border-collapse: collapse;"
|- style="vertical-align: top;"
| valign="top" width="11%" style="width: 66px; border: 1px solid rgb(0, 0, 0);" |
Value

| valign="top" width="100%" style="width: 556px; border: 1px solid rgb(0, 0, 0);" |
A constant that fits into a LONG , indicating how much time must be waited before the waiting is terminated.

|}
</div>
<span style="font-family: Arial;"> </span>

All RS-232 serial statements and functions(except INKEY) that use the hardware UART or software UART, will halt the program until a character is received. Only with buffered serial input you can process your main program while the buffer received data on the background.

<span style="font-family: Arial;"> </span>

[[File:Notice.jpg|left|Notice.jpg]] $TIMEOUT is an alternative for normal serial reception. It is not intended to be used with buffered serial reception.

<span style="font-family: Arial;"> </span>

When you assign a constant to $TIMEOUT, you actual assign a value to the internal created value named <span style="font-style: italic;">___TIMEOUT</span>.

<span style="font-family: Arial;"> </span>

This value will be decremented in the routine that waits for serial data. When it reaches zero, it will terminate.

<span style="font-family: Arial;"> </span>

So the bigger the value, the longer the wait time before the timeout occurs. The timeout is not in seconds or microseconds, it is a relative number. Only the speed of the oscillator has effect on the duration. And the value of the number of course.

<span style="font-family: Arial;"> </span>

When the time out is reached, a zero/null will be returned to the calling routine. Waitkey() will return 0 when used with a byte. When you use INPUT with a string, the timeout will be set for every character. So when 5 characters are expected, and they arrive just before the timeout value is reached, it may take a long time until the code is executed.

<span style="font-family: Arial;"> </span>

When the timeout occurs on the first character, it will return much faster.

<span style="font-family: Arial;"> </span>

When you already sent data, this data will be returned. For example, "123" was sent but a RETURN was never sent, INPUT will return "123". While without the $TIMEOUT, INPUT will not return until a RETURN is received.

<span style="font-family: Arial;"> </span>

[[File:Notice.jpg|left|Notice.jpg]]When you activate $TIMEOUT, and your micro has two UARTS(Mega128 for example) it will be active for both UART0 and UART1. And for an ATMEGA2560 with 4 UARTS, it will be enabled for all 4 UARTS, but only when no serial input buffer is configured.

 

$TIMEOUT is also supported by the software UART. In fact, when you enable it for the hardware UART, you enable it for the software UART as well.

<span style="font-family: Arial;"> </span>

<span style="font-family: Arial;"> </span>

= <span class="f_Header">See Also</span> =

[[INPUT]] , [[WAITKEY]]

<span style="font-family: Arial;"> </span>

<span style="font-family: Arial;"> </span>

= <span class="f_Header">Example</span> =

<br/><source lang="bascomavr">
'-----------------------------------------------------------------------------------------
'name : timeout.bas
'copyright : (c) 1995-2005, MCS Electronics
'purpose : demonstration of the $timeout option
'micro : Mega48
'suited for demo : yes
'commercial addon needed : no
'-----------------------------------------------------------------------------------------

$regfile = "m48def.dat" ' specify the used micro
$crystal = 8000000 ' used crystal frequency
$baud = 19200 ' use baud rate
$hwstack = 32 ' default use 32 for the hardware stack
$swstack = 10 ' default use 10 for the SW stack
$framesize = 40 ' default use 40 for the frame space

'most serial communication functions and routines wait until a character
'or end of line is received.
'This blocks execution of your program. SOmething you can change by using buffered input
'There is also another option : using a timeout
'$timeout Does Not Work With Buffered Serial Input

Dim Sname As String * 10
Dim B As Byte
Do
$timeout = 1000000
Input "Name : " , Sname
Print "Hello " ; Sname

$timeout = 5000000
Input "Name : " , Sname
Print "Hello " ; Sname
Loop

'you can re-configure $timeout
</source><br/>{{Languages}}

[[Category:BASCOM_Language_Reference]]